Single chain-urokinase binds to oxidized fibrin(ogen) derivatives.

Single chain- urokinase (scu-PA), in contrast to two chain urokinase, is a physiological plasminogen activator of fibrin selectivity. The mechanism of selective fibrinolysis of scu- PA has not been clarified up to now. This study has shown that fibrin selectivity might involve oxidative processes. Binding studies with immobilized oxidized fibrinogen degradation products (FDP) demonstrated higher affinity of scu-PA to oxidized than to unmodified FDP. The fibrin(ogen) domain responsible for this oxidant mediated increase of scu-PA affinity is localized in the D-subunit of fibrin(ogen). Thus, experimental data upon the interaction of scu-PA with fibrin(ogen) using oxidized and I- labelled fibrin(ogen) might be interpreted with caution: the oxidized product may behave in a distinct manner than the unoxidized, native, one. Activated leukocytes release large amounts of scu-PA and of oxidants of the chloramine type. The oxidants could contribute significantly to fibrinolysis and proteolysis in areas of inflammation, preparing fibrin for its specific degradation. The present data support the concept of an involvement of oxidative processes in the fibrinolytic pathway.

Chronic lymphocytic leukemia with two cellular populations: a biphenotypic or biclonal disease.

A case of CLL with two different cellular populations is reported. A 50-year-old man was evaluated for persistent absolute lymphocytosis. A peripheral blood smear revealed numerous small lymphocytes (83% of white blood cells counted). Frequent Grumpecht shadows were present, too. On bone marrow aspirate smears lymphocytes comprised 85% of the total cells counted, and the bone marrow biopsy showed a mixed nodular-interstitial infiltration pattern. The immunophenotypic study showed two different leukemic populations. The first one (comprising 79% leukemic cells) was CD5+, CD19+, CD10-, CD20+, CD18-, CD22-, CD23+ +, lambda dim, and FMC7-. The second population (comprising 21% leukemic cells) was CD5+, CD19+, CD10-, CD20+, CD18+, CD22+, CD23+, lambda+ +, and FMC7+. Gene rearrangement studies detected the germline and one rearranged band in Jk blot with each restriction endonuclease. In the Jh blot the germline and two rearranged bands were detected with EcoRI and BamHI and three rearranged bands with HindIII. The JBI/JBII blot detected only the germline band. The detection of three rearranged bands was interpreted as evidence of the presence of at least two monoclonal populations of cells with the same light chain restriction.

[Sudan black B-positive acute lymphoblastic leukemia]. / Leucemia aguda linfoblástica negro sudan B positivo.

Inasmuch as Sudan black B stain is highly specific for myeloid cells and since over 3% positive blast cells meet the needs of diagnosis for myeloblastic leukaemias, we had the opportunity to study a 27 year-old male with acute leukaemia whose morphological, cytochemical, immunocytochemical (HLA-DR, CD-10, CD-19, CD-20, CD-21 all positive) and ultrastructural features were clearly in accordance with acute lymphoblastic leukaemia, except for 42% Sudan black B positivity of the bone marrow blast cells. The practical interest of this case comes from the necessity to take this rare ALL case into account.

[Richter syndrome: morphologic transformation with persistence of the same phenotype]. / Síndrome de Richter: transformación morfológica con persistencia del mismo fenotipo.

Richter's syndrome is termed as the occurrence of a high-grade lymphoma along with a chronic lymphocytic leukaemia. We report a patient diagnosed as having a CLL evolving into an immunoblastic lymphoma. In spite of this morphologic change, the same identical immunophenotype remained in both types of cells assessed, that is, CLL-type lymphocytes and immunoblastic and lymphoplasmocytoid cells. This event appears to favour the common clonal origin of these two entities.

[A new case of congenital leukemia with leukemia cutis]. / Un nuevo caso de leucemia congénita con leucemia cutis.

Congenital leukaemia is a condition occurring very rarely. In a recent review in 1993, 175 cases are reported, 25-30% of them being well documented as leukaemia cutis. We reported a new case of congenital leukaemia diagnosed as an acute non lymphoblastic leukaemia M4 (FAB) and diagnosed at birth. It involves a newborn female at 42 weeks of gestational age. The most relevant clinical features were hepatomegaly and cutaneous petechial lesions along with a generalized distribution of nodules. From the blood peripheral count, leukocytosis is observed (177 x 10(9)/L) with 48% blasts of myeloid immunophenotype. The coagulation studies were consistent with a disseminated intravascular coagulation syndrome. A biopsy carried out on a cutaneous nodule, revealed diffuse dermoepidermic infiltration by immature cells of myeloid lineage, with cellularity and count similar to that of bone marrow and peripheral blood. The karyotype in the peripheral blood was normal. Infectious and immune causes were excluded as well as constitutional illnesses associated with unstable haematopoiesis. The family rejected treatment with chemotherapy and the baby died on day 53 of life due to progressive leukocytosis and concurrent infection. Our case, like 80% of the cases reported, is of myeloid origin and confirms the fatal evolution of untreated congenital leukaemia.